Transmission Brake Hub Layout for Compact Oil-Fed Friction Plates
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Solution Overview
Problem
Existing automatic transmissions face challenges in achieving a compact arrangement of brake components while preventing rotation of the hub member with spline-engaged friction plates and efficiently supplying lubrication hydraulic oil to the friction plates, leading to issues with backlash and lubrication stagnation.
Innovation Solution
The automatic transmission design includes a hub member joined to the transmission casing with a splined region for spline-engagement, a second hub member forming a lubrication oil supply passage, and a third hub member to form part of the lubrication oil supply passage, with all hub members made from the same material to equalize thermal expansion, allowing for a compact arrangement and efficient lubrication oil supply.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the biasing member, engagement hydraulic pressure chamber, and disengagement hydraulic pressure chamber are disposed on the driven source side with respect to the piston, then the brake can be engaged and disengaged reliably, but the axial dimension of the brake becomes large
Solution Approach 1:
The patent applies dimensionality change by moving the biasing member, engagement hydraulic pressure chamber, and disengagement hydraulic pressure chamber from the axial direction to the radial direction of the piston. This allows these components to be arranged in a compact configuration without increasing the axial dimension of the brake, while maintaining reliable brake engagement and disengagement functionality.
2Reliability
If the hub member is spline-engaged with the transmission casing to prevent rotation, then the friction plates can be properly engaged, but backlash occurs in the joined portion and connected portion, leading to inefficient lubrication hydraulic oil supply
Solution Approach 1:
The patent segments the hub member into a first hub member and a second hub member. The first hub member is spline-engaged with the transmission casing to prevent rotation and ensure friction plate engagement stability, while the second hub member is fittingly engaged with the transmission casing to provide a backlash-free connection for efficient lubrication hydraulic oil supply. This segmentation allows each part to fulfill its specific function without the drawbacks of the other.
3Productivity
If the drum member and hub member are joined respectively to the transmission casing and rotary member, then lubrication hydraulic oil can be supplied efficiently, but lubrication hydraulic oil may stagnate in the vicinity of the inner peripheral surface of the drum member
Solution Approach 1:
The patent extracts the lubrication hydraulic oil supply function from the drum member and concentrates it in the hub member through the second hub member. By providing a dedicated lubrication hydraulic oil supply passage in the hub member that is fittingly engaged with the transmission casing, the system ensures efficient and continuous lubrication hydraulic oil supply to the friction plates without stagnation in the drum member vicinity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design achieves a compact arrangement of brake components, prevents rotation of the hub member during brake engagement, and ensures efficient lubrication hydraulic oil supply to the friction plates, enhancing the transmission's operational efficiency and reliability.
Implementation Method 1
a piston for engaging a plurality of friction plates is biased by a spring and an engagement hydraulic pressure such that it is moved in an engagement direction
Implementation Method 2
then biased by an engagement hydraulic pressure such that it is moved from the zero-clearance position to an engagement position
Implementation Method 3
the engagement hydraulic pressure is released, and the disengagement hydraulic pressure is supplied, from a state in which the piston 206 is at the engagement position. As a result, the piston 206 is biased in the disengagement direction such that it is moved to the disengagement position
Data Source
AI summary
Provided is an automatic transmission with a compact arrangement that prevents rotation of a hub member, and efficiently supplies lubrication hydraulic oil to the friction plates. The automatic transmission comprises a brake in which a plurality of friction plates are arranged between the hub member and a drum member, wherein a biasing member, an engagement hydraulic pressure chamber, and a disengagement hydraulic pressure chamber are arranged radially inward of the friction plates at positions radially overlapping each other. The hub member comprises: a first hub member comprising a cylindrical portion having a splined region with which the friction plates are spline-engaged, wherein the first hub member s spline-engaged with a transmission casing; and a second hub member formed with a part of a lubrication oil supply passage, wherein the second hub member is fittingly engaged with the transmission casing such that it is connected to a valve body.